POS1233 CLINICAL, SEROLOGICAL AND MUSCLE SHEAR WAVE ELASTOGRAPHY ASSESSMENT IN PATIENTS WITH IDIOPATHIC INFLAMMATORY MYOPATHIES
Authors: Y. Xin, J. Gao, Y. LI, F. Liu, J. Zhu
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of systemic autoimmune disorders characterized by various degrees of muscle weakness and inflammation. Shear wave elastography may be as a potential noninvasive quantitative imaging biomarker. <h3>Objectives</h3> The objective of this work was to describe the demographic, clinical and serological characteristics of IIM patients, and to evaluate the role of shear wave elastography in detecting muscle damage. <h3>Methods</h3> We enrolled 14 patients with IIM fulfilling the EULAR/ACR 2017<sup>[1]</sup> and having muscle involvement. Shear wave elastography were performed on rectus femoris (RF), deltoid (DEL), biceps brachii (BB) and sternocleidomastoid (SCM) muscles in these patients and 20 healthy controls along the transverse and longitudinal axes, respectively. Demographic, clinical, and serological characteristics were collected from patients' medical records. <h3>Results</h3> The study included 14 patients with IIM (5 dermatomyositis, 7 immune-mediated necrotizing myopathy, 2 anti-synthetase syndrome). The mean age at diagnosis was 52.93 (±12.99) years, with 9 females (64.3%). The demographic, clinical, serological characteristics of the patients were summarized in Table 1. Muscle ultrasound of IIM patients revealed increased muscle and fascia echogenicity, indicating obvious edema (Figure 1). The shear wave velocity and dispersion slope of RF (1.39 vs. 1.60 m/s, 6.70 vs. 7.59 kHz/[m/s]; 1.82 vs. 1.95 m/s, 7.95 vs. 10.10 kHz/[m/s]), DEL (1.28 vs. 1.41 m/s, 7.01 vs. 7.37 kHz/[m/s]; 2.20 vs. 2.57 m/s, 11.05 vs. 14.39 kHz/[m/s]) and BB (1.29 vs. 1.43 m/s, 7.12 vs. 7.54 kHz/[m/s]; 2.28 vs. 2.60 m/s, 11.74 vs. 13.49 kHz/[m/s]) in myositis patients are significantly lower than those in healthy controls on transverse and longitudinal axes, while SCM (6.94 vs. 7.25 kHz/[m/s], 9.49 vs. 10.51 kHz/[m/s]) only has differences in the dispersion slope (<i>p</i> &lt; 0.05). We further calculated the sum of viscoelasticity of these four groups of muscles. The overall shear wave velocity (10.82 vs. 11.83 m/s, 16.72 vs. 18.6 m/s) and dispersion slope (55.54 vs. 59.49 kHz/[m/s], 80.46 vs. 96.99 kHz/[m/s]) of myositis patients were lower than that of the healthy controls, which was consistent across transverse and longitudinal axes (<i>p</i> &lt; 0.05). Correlation analysis identified significant negative correlation between CK and LDH and muscle viscoelasticity, with correlation coefficients of -0.56 to -0.60 and -0.57 to -0.71, respectively (<i>p</i> &lt; 0.05). <h3>Conclusion</h3> The viscoelasticity of muscle in IIM patients was significantly decreased, which was moderately to strongly correlated with muscle injury markers. Shear wave elastography can quantitatively evaluate muscle injury, it may serve as an imaging marker for the diagnosis and activity evaluation of myositis. <h3>Reference</h3> [1]Lundberg IE, et al. 2017 European League Against Rheumatism/American College of Rheumatology Classification Criteria for Adult and Juvenile Idiopathic Inflammatory Myopathies and Their Major Subgroups. Arthritis Rheumatol. 2017;69:2271-82. <h3>Acknowledgements</h3> This study was supported by the National Natural Science Foundation of China (No. 82071930). <h3>Disclosure of Interests</h3> None Declared.